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Old 03-27-2013, 02:54 AM   #1 (permalink)
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Neutral High Revs Question

I have been trying to put my tranny into neutral when I see I am coming up to a red light or slowing down for any reason. What I have noticed, however, is that I will put it into neutral and the RPMs will lower like normal, but when I come to a complete stop, the RPMs stay relatively high and when I put it into drive the RPMs go down to a "normal" idle speed.
Also, I have noticed the RPMs fluctuate a lot. Some days are good and some days, well... When idling or during normal operation, the revs will be at a normal speed, but on bad days, the RPMs can be close to or above two for idle and almost three at speed.
I've also noticed when switching gears, the tranny can be a little "jumpy", instead of a smooth transition into the next gear. This doesn't happen often, and I can't narrow it down to cold days or hot days, engine cold or engine hot, at speed or idle into accelerating, etc.
The bad days are few and far in between, but I don't know if these are separate issues or symptoms of a bigger problem. I do know the ATF is a little fuller then it should and I was going to change it, since I don't know when it was last changed (and we have had the car for a decent time now), but I can't imagine this to be the fix-it for all these issues. I am planning on changing the fluid on Thursday or Friday, but I was wondering if anybody had any insight on this beforehand.

Thanks!
Jeff

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Old 03-27-2013, 05:10 AM   #2 (permalink)
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The engine idles faster in neutral because it isn't applying any force to your wheels. When you place the gear selector into D, the engine begins spinning fluid in the torque converter and attempts to move the wheels, which puts a load on the engine. This is the reason the car creeps forward when you release the brake pedal while the car is idling.

Idle RPM depends on factors such as speed when coasting and temperature. My car will idle at 2000+ RPM if it's cold enough outside. Not sure what is considered normal for your car.
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Old 03-27-2013, 09:55 PM   #3 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
The engine idles faster in neutral because it isn't applying any force to your wheels. When you place the gear selector into D, the engine begins spinning fluid in the torque converter and attempts to move the wheels, which puts a load on the engine. This is the reason the car creeps forward when you release the brake pedal while the car is idling.
OK, so I have to keep a load on the ICE in order for the revs to stay a little lower, which is why when coasting (when there is still a load), neutral works, but at a stop (when there is no load left), neutral doesn't work, because the ICE needs something to work on. I think that's what your saying, correct me if I'm wrong.

If that is the case, is there a way to trick the ICE or computer into thinking there is a load on the engine, when I am at a stop and in neutral, so that it will lower the RPMs to the same or lower then when at a stop in 'D'.

Quote:
Originally Posted by redpoint5 View Post
Idle RPM depends on factors such as speed when coasting and temperature. My car will idle at 2000+ RPM if it's cold enough outside. Not sure what is considered normal for your car.
OK, so it sounds like another bonus to having a grill block (and associated faster warm-up times) is to make the engine get hot (or at least to operating temp.) and lower the RPMs accordingly. (I guess?)

Jeff

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